Wadsworth Center, New York State Department of Health, and Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, P.O. Box 509, Albany, New York 12201-0509, United States.
Environ Sci Technol. 2011 Dec 1;45(23):10140-7. doi: 10.1021/es203002a. Epub 2011 Nov 8.
Thyroid hormones (THs) are essential for the regulation of growth and development in both humans and wildlife. Until recently, TH concentrations in the tissues of animals have been examined by immunoassay (IA) methods. IA methods are sensitive, but for TH analysis, they are compromised by a lack of adequate specificity. In this study, we determined the concentrations of six THs, L-thyroxine (T(4)), 3,3',5-triiodo-L-thyronine (T(3)), 3,3',5'-triiodo-L-thyronine (rT(3)), 3,5-diiodo-L-thyronine (3,5-T(2)), 3,3'-diiodo-L-thyronine (3,3'-T(2)), and 3-iodo-L-thyronine (3-T(1)), in the serum of humans (n = 79) and wild Baikal seals (n = 37), by isotope ([(13)C(6)]-T(4))-dilution liquid chromatography (LC)-tandem mass spectrometry (MS/MS), and compared the TH levels with those measured by an electrochemiluminescent immunoassay (ECLIA) method. T(3) and T(4) were detected in all serum samples of both humans and Baikal seals, whereas T(1), 3,3'-T(2), and 3,5-T(2) were below the limit of detection (LOD). rT(3) was detected in Baikal seal sera at concentrations higher than T(3) in 28 seal samples, indicating an anomaly in deiodinase activity in Baikal seals. In humans, regression analyses of TH concentrations, measured by ECLIA and LC-MS/MS methods, showed significant correlations for T(4) (r = 0.852) and T(3) (r = 0.676; after removal of a serum sample with abnormal T(3) levels). In Baikal seals, a low correlation coefficient (r = 0.466) for T(4) levels and no correlation for T(3) levels (p = 0.093) were found between ECLIA and LC-MS/MS methods. These results suggest that interference by a nonspecific reaction against anti-T(3) and anti-T(4) antibodies used in the ECLIA can contribute to inaccuracies in TH measurement in Baikal seals. When the relationship between concentrations of THs in sera and dioxin-like toxic equivalents in blubber samples of Baikal seals (n = 19) was examined, a significantly negative correlation was found for serum T(4) levels measured by the LC-MS/MS method, but not for those measured by ECLIA. Thus, our results indicate that the LC-MS/MS method is more reliable and accurate for the elucidation of alteration in circulating TH levels in wildlife, as caused by environmental and physiological factors.
甲状腺激素 (THs) 对人类和野生动物的生长和发育调节至关重要。直到最近，动物组织中的 TH 浓度一直通过免疫分析 (IA) 方法进行检测。IA 方法很灵敏，但对于 TH 分析，由于缺乏足够的特异性而受到限制。在这项研究中，我们通过同位素稀释液相色谱 (LC)-串联质谱 (MS/MS) 法[(13)C(6)]-T(4) 测定了人类 (n = 79) 和野生贝加尔海豹 (n = 37) 血清中的六种 THs，L-甲状腺素 (T(4))、3,3',5-三碘-L-甲状腺素 (T(3))、3,3',5'-三碘-L-甲状腺素 (rT(3))、3,5-二碘-L-甲状腺素 (3,5-T(2))、3,3'-二碘-L-甲状腺素 (3,3'-T(2)) 和 3-碘-L-甲状腺素 (3-T(1))，并将 TH 水平与通过电化学发光免疫分析 (ECLIA) 方法测量的水平进行了比较。T(3)和 T(4)在人类和贝加尔海豹的所有血清样本中均有检测到，而 T(1)、3,3'-T(2)和 3,5-T(2)低于检测限 (LOD)。rT(3) 在贝加尔海豹血清中的浓度高于 28 个海豹样本中的 T(3)，表明贝加尔海豹脱碘酶活性异常。在人类中，通过 ECLIA 和 LC-MS/MS 方法测量的 TH 浓度的回归分析显示，T(4)(r = 0.852)和 T(3)(r = 0.676；在去除 T(3)水平异常的血清样本后)呈显著相关性。在贝加尔海豹中，T(4)水平的相关系数较低 (r = 0.466)，T(3)水平无相关性 (p = 0.093)，表明 ECLIA 和 LC-MS/MS 方法之间存在误差。这些结果表明，ECLIA 中使用的抗 T(3)和抗 T(4)抗体的非特异性反应可能导致贝加尔海豹 TH 测量不准确。当检查贝加尔海豹 (n = 19) 血清和皮下脂肪样本中二恶英类似物毒性当量与 TH 浓度之间的关系时，LC-MS/MS 方法测量的血清 T(4)水平呈显著负相关，但 ECLIA 方法测量的则没有相关性。因此，我们的结果表明，LC-MS/MS 方法对于阐明环境和生理因素引起的野生动物循环 TH 水平的变化更为可靠和准确。
